September weather forecast
Lewistown, MT

Weather in September

The first month of the autumn, September, is still a comfortable month in Lewistown, Montana, with an average temperature varying between 47.1°F (8.4°C) and 67.5°F (19.7°C).

Temperature

In Lewistown, the average high-temperature in September decreases from a warm 78.1°F (25.6°C) in August to an enjoyable 67.5°F (19.7°C). In Lewistown, the average low-temperature is 47.1°F (8.4°C).

Humidity

In Lewistown, the average relative humidity in September is 52%.

Rainfall

In Lewistown, it is raining for 8.7 days, with typically 1.02" (26mm) of accumulated precipitation. Throughout the year, there are 126.2 rainfall days, and 17.83" (453mm) of precipitation is accumulated.

Snowfall

January through June, September through December are months with snowfall in Lewistown, Montana. September is the first month it typically snows in Lewistown. Throughout September, in the average 1 snowfall days, it receives 1.3" (33mm) of snow. In Lewistown, during the entire year, snow falls for 83.4 days and aggregates up to 45.51" (1156mm) of snow.

Daylight

In Lewistown, the average length of the day in September is 12h and 32min.
On the first day of September, sunrise is at 6:37 am and sunset at 7:57 pm. On the last day of the month, sunrise is at 7:15 am and sunset at 6:59 pm MDT.

Sunshine

The average sunshine in September in Lewistown is 10h.

UV index

In September, the average daily maximum UV index is 4. A UV Index value of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV rays for average individuals.
Note: The average daily UV index of 4 in September transform into the following instructions:
Take precautions - Protection against skin and eye damage is obliged. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.
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FAQ

What is the average humidity in September in Lewistown?

In September, the average relative humidity in Lewistown, Montana, is 52%.

How much does it rain in Lewistown in September?

In Lewistown, in September, during 8.7 rainfall days, 1.02" (26mm) of precipitation is typically accumulated.

When does it start snowing in Lewistown?

September is the first month it typically snows in Lewistown, Montana. Throughout September, in the average 1 snowfall days, it receives 1.3" (33mm) of snow.

How many hours of daylight does Lewistown have in September?

In September, the average day length in Lewistown, Montana, is 12h and 32min.

When are sunrise and sunset in September in Lewistown?

In September, on the first day of the month, sunrise is at 6:37 am and sunset at 7:57 pm. On the last day of the month, in Lewistown, Montana, sunrise is at 7:15 am and sunset at 6:59 pm MDT.

How long on average sun shines in September in Lewistown?

In Lewistown, the average sunshine duration in September is 10h.

What is the UV index reading in September in Lewistown?

In Lewistown, Montana, the average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a medium hazard to health from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall days
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Lewistown, MT

Average temperature in September - Lewistown, MT
  • Average high temperature in September: 67.5°F

The warmest month (with the highest average high temperature) is July (78.8°F).
The months with the lowest average high temperature are February and December (29.1°F).

  • Average low temperature in September: 47.1°F

The month with the highest average low temperature is August (54.5°F).
The coldest month (with the lowest average low temperature) is February (15.3°F).

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Average pressure in September
Lewistown, MT

Average pressure in September - Lewistown, MT
  • Average pressure in September: 29.94"Hg

The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.85"Hg).

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Average wind speed in September
Lewistown, MT

Average wind speed in September - Lewistown, MT
  • Average wind speed in September: 8.5mph

The windiest months (with the highest average wind speed) are January, April and October (9.9mph).
The calmest month (with the lowest average wind speed) is August (7.4mph).

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Average humidity in September
Lewistown, MT

Average humidity in September - Lewistown, MT
  • Average humidity in September: 52%

The month with the highest relative humidity is February (79%).
The month with the lowest relative humidity is August (47%).

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Average rainfall in September
Lewistown, MT

Average rainfall in September - Lewistown, MT
  • Average rainfall in September: 1.02"

The wettest month (with the highest rainfall) is May (3.39").
The driest month (with the least rainfall) is December (0.71").

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Average rainfall days in September
Lewistown, MT

Average rainfall days in September - Lewistown, MT
  • Average rainfall days in September: 8.7 days

The month with the highest number of rainy days is May (19.3 days).
The month with the least rainy days is January (5.4 days).

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Average snowfall in September
Lewistown, MT

Average snowfall in September - Lewistown, MT
  • Average snowfall in September: 1.3"

The month with the highest snowfall is April (9.13").
The months with the least snowfall are July and August (0").

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Average snowfall days in September
Lewistown, MT

Average snowfall days in September - Lewistown, MT
  • Average snowfall days in September: 1 days

The month with the highest number of snowfall days is February (15.2 days).
The months with the least snowfall days are July and August (0 days).

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Average daylight in September /
Average sunshine in September
Lewistown, MT

Average daylight in September / Average sunshine in September - Lewistown, MT
  • Average daylight in September: 12h and 32min

The month with the longest days is June (Average daylight: 15h and 50min).
The month with the shortest days is December (Average daylight: 8h and 35min).

  • Average sunshine in September: 10h and 0min

The month with the most sunshine is July (Average sunshine: 11h and 48min).
The month with the least sunshine is February (Average sunshine: 5h and 30min).

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Average sunshine days in September
Lewistown, MT

Average sunshine days in September - Lewistown, MT
  • Average sunshine days in September: 19.3 days

The month with the most sunshine days is September (19.3 days).
The month with the least sunshine days is April (8.3 days).

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Average UV index in September
Lewistown, MT

Average UV index in September - Lewistown, MT
  • Average UV index in September: 4

The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, March, April, October, November and December (UV index 2).

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Average cloud cover in September
Lewistown, MT

Average cloud cover in September - Lewistown, MT
  • Average cloud cover in September: 23

The month with the most cloud cover is February (Cloud cover 45).
The month with the least cloud cover is July (Cloud cover 16).

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Average visibility in September
Lewistown, MT

Average visibility in September - Lewistown, MT
  • Average visibility in September: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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